The expansibility, upgrade and compatible intercommunication capability of a rapid developed IP network are very strong, and flexibilities of the upgrade, expansibility and intercommunication of a traditional communication network are comparatively poor and they are limited by the transmission modes and service types, and the universality of newly established networks is also relatively poor, which is inappropriate for intercommunication management. Therefore, in the process of the traditional communication network facing the upgrade and application expansion, it is considered whether to establish repetitive networks respectively or to fully utilize the existing or common resources to achieve the object of network upgrade and application expansion, and how to be able to achieve this object is a problem considered by all the skilled in the art.
The Pseudo Wire (PW) technology is a solution proposed with respect to a converged communication network in the future, and it is a technology of providing imitated traditional 1 layer and 2 layer network services based on a packet switched network. The pseudo wire technology is almost applied to all networks, which enables the Multi-Protocol Label Switch (MPLS) technology to implement a real convergence of access network and metropolitan area network. A pseudo wire is a point-to-point connection between Provider Edge (PE) nodes, an establishment mechanism of the pseudo wire is defined in the RFC4447 of Internet Engineering Task Force (IETF), the pseudo wire is established by using a Label Distribute Protocol (LDP) as a signaling mechanism, and label switching and parameter negotiations of the pseudo wire are performed. Wherein, a control word negotiation is only one of the pseudo wire parameter negotiations, only when Control words (C-Bit) in LDP mapping message mutually announced by two Provider Edges (PE) establishing the pseudo wire are consistent, the control words of the pseudo wire can be negotiated successfully, and only when each control word in the LDP mapping message mutually announced is 1, it can be negotiated that the PW supports the control words. All the ultimate negotiation results in other situations are that the PW does not support the control words (refer to the RFC4447 protocol for the specific control word negotiation rules).
FIG. 1 is schematic diagram of a network of the Single Segment Pseudo Wire (SS-PW) control word negotiation in the related art, a PE1 and a PE2 will have the problem of inconsistency between negotiation results and configurations in the following scenario. The following steps are specifically included.
In step 101, the PE2 configures that the PW does not support a control word in local, and sends label mapping message carrying a C-Bit of 0 to the PE1.
In step 102, the PE1 configures that the PW supports the control word in local and sends label mapping message carrying a C-Bit of 0 to the PE2.
An operating way in this step is determined according to the RFC4447, and the RFC4447 formulates that, if the C-Bit in the label mapping message firstly sent by an opposite terminal to a current terminal is 0, it is indicated that the opposite terminal does not support the control word, and no matter whether a local configuration supports the control word or not subsequently, the label mapping message with the C-Bit of 0 is still announced to the opposite terminal.
In step 103, the PE1 makes a successful local negotiation with respect to the PW, and the control word negotiation result is a way of not supporting.
In step 104, the PE2 receives the label mapping message carrying the C-Bit of 0 announced by the opposite terminal, a local negotiation with respect to the PW is successful, and the negotiation result is a way of not supporting.
At the point, two terminals of the PW make a successful negotiation, and the control word negotiation result is a way of not supporting, which is represented as NegoCbit=0.
In step 105, a local configuration of the PE2 is deleted, a local pseudo wire is canceled, and label cancel message is sent to the PE1.
In step 106, the PE1 cancels the pseudo wire after receiving the label cancel message of the PE2, and replies label release message to the PE2.
At the point, the PW is canceled, and a control word negotiation result is unknown, which is represented as NegoCbit=X.
In step 107, the PE2 reconfigures that the PW locally supports the control word, and sends the label mapping message carrying the C-Bit of 0 to the PE1.
Since the PE2 receives the label mapping message carrying the C-Bit of 0 sent by the PE1 in the step 104, according to the provision in the RFC4447 that, if the C-Bit in the label mapping message firstly sent by the opposite terminal to the current terminal is 0, it is indicated that the opposite terminal does not support the control word, and no matter whether a local configuration supports the control word or not subsequently, the label mapping message with the C-Bit of 0 is still announced to the opposite terminal, even though the PE2 configures that the PW supports the control word in local, it still sends the label mapping message carrying the C-Bit of 0 to the PE1.
In step 108, the PE2 makes a successful local negotiation with respect to the PW, and the control word negotiation result is a way of not supporting.
In step 109, after receiving the label mapping message carrying the C-Bit of 0 announced from the PE2, the PE1 makes a successful local negotiation with respect to the PW, and the control word negotiation result is a way of not supporting.
Ultimately, two terminals of the PW make a successful negotiation, and the control word negotiation result is a way of not supporting.
It can be seen from the description of the above negotiation process that, in this timing sequence scenario, when the PE2 modifies the local control word configuration properties (that is, not supporting is modified as supporting) in step 107, according to the C-Bit of 0 in the mapping message announced by the PE1 to the PE2 previously, the PE2 judges that the PE1 is in the way of not supporting the control word (but actually the PE1 supports the control word), and consequently carries the C-Bit of 0 in the label mapping message announced to the opposite terminal, thus eventually resulting in that the local configurations of the PE1 and PE2 are all in the way of supporting the control words, but they still do not support the control words according to the existing negotiation results, which causes the inconsistency between the configurations and the expected negotiation results.
FIG. 2 is schematic diagram of a network of the Multiple Segment Pseudo Wire (MS-PW) control word negotiation in the related art, a pseudo wire Terminating PE (T-PE) and a pseudo wire Switching PE (S-PE) are included, a T-PE1 and a T-PE3 will have the problem of inconsistency between negotiation results and configurations in the following scenario. The following steps are specifically included.
In step 201, the T-PE3 configures that the PW does not support a control word in local, and sends label mapping message carrying a C-Bit of 0 to the S-PE2, the S-PE2 configures that the PW supports the control word in local, but the S-PE2 sends the label mapping message carrying the C-Bit of 0 to the T-PE1.
In step 202, the T-PE1 configures that the PW supports the control word in local, but sends the label mapping message carrying the C-Bit of 0 to the S-PE2, and the S-PE2 sends the label mapping message carrying the C-Bit of 0 to the T-PE3.
An operating way of this step is determined according to the RFC4447, and the RFC4447 formulates that, if the C-Bit in the label mapping message firstly sent by an opposite terminal to a current terminal is 0, it is indicated that the opposite terminal does not support the control word, and no matter whether a local configuration supports the control word or not subsequently, the label mapping message with the C-Bit of 0 is still announced to the opposite terminal. Therefore, in this step, the T-PE1 sends the label mapping message carrying the C-Bit of 0 to the S-PE2.
In step 203, the T-PE1 makes a successful local negotiation with respect to the PW, and the control word negotiation result is a way of not supporting.
In step 204, the T-PE3 receives the label mapping message carrying the C-Bit of 0 announced by the opposite terminal, a local negotiation with respect to the PW is successful, and the negotiation result is a way of not supporting.
At the point, two terminals of the PW make a successful negotiation, and the control word negotiation result is a way of not supporting, which is represented as NegoCbit=0.
In step 205, a local configuration of the T-PE3 is deleted, a local pseudo wire is canceled, label cancel message is sent to the S-PE2, and the S-PE2 sends the label cancel message to the T-PE1.
In step 206, the S-PE2 receives the label cancel message of the T-PE3 and replies a label release message to the T-PE3, and the S-PE2 continues to send the label cancel message to the T-PE1.
In step 207, the T-PE1 receives the label cancel message of the S-PE2 and replies the label release message to the S-PE2.
At the point, the negotiation with respect to the PW is canceled, and a control word negotiation result is unknown, which is represented as NegoCbit=X.
In step 208, the T-PE3 reconfigures that the PW locally supports the control word, and sends the label mapping message carrying the C-Bit of 0 to the T-PE1 via the S-PE2.
In step 209, the T-PE3 makes a successful local negotiation with respect to the PW, and the control word negotiation result is a way of not supporting.
In step 210, after receiving the label mapping message carrying the C-Bit of 0, the T-PE1 makes a successful local negotiation with respect to the PW, and the control word negotiation result is a way of not supporting.
Ultimately, two terminals of the PW make a successful negotiation, and the control word negotiation result is a way of not supporting.
The above multiple segment pseudo wire negotiation process has the same problem as that in the single segment pseudo wire negotiation process, as shown in FIG. 2, at first, the local control word configuration ways of the T-PE1, S-PE2 and T-PE3 are respectively: supporting control word, supporting control word, and not supporting control word. when the T-PE3 modifies the local control word configuration properties (that is, not supporting is modified as supporting), according to the C-Bit of 0 in the mapping message announced by the S-PE2 to the T-PE3 previously, the T-PE3 judges that the S-PE2 is in the way of not supporting the control word (but actually the S-PE2 supports the control word), and consequently carries the C-Bit of 0 in the label mapping message announced to the opposite terminal, thus eventually resulting in that the local configurations of the T-PE1, S-PE2 and T-PE3 are all in the way of supporting the control words, but they still do not support the control words according to the existing negotiation results, which causes the inconsistency between the configurations and the expected negotiation results.